Predicting the Retention of Cs in Individuals

Abstract

Various factors have been offered to explain and/or predict the wide variation in the retention of Cs among humans. For example, the biological half-time of Cs has been expressed as an increasing function of body mass and also as an increasing function of age throughout life. Some early investigators attempted to describe accumulation of Cs in the body in terms of discrimination factors between Cs and the chemically similar element K, but such factors were found to oversimplify the relation between Cs and K and they were soon abandoned. In this paper it is shown that K may be a useful index, after all, for predicting the retention patterns of Cs in individuals. A predictive model for individuals is constructed, using observed relationships between the mass of total-body K (Kt) and the parameters in the standard two-exponential retention model for Cs.

Uncertainties in Cancer Risk Coefficients for Environmental Exposure to Radionuclides. An Uncertainty Analysis for Risk Coefficients Reported in Federal Guidance Report No. 13

“…There have been numerous studies of the biological behavior of radiocesium in human subjects exposed under natural or controlled conditions (Leggett 1986, ICRP 1989. It has been established that cesium is somewhat uniformly distributed in soft tissues by a few days after intake and that whole-body retention can be approximated reasonably well by a single biological half-time, although one or two additional short-term half-times have been identified in some injection studies.…”

Reliability of Current Biokinetic and Dosimetric Models for Radionuclides: A Pilot Study

“…Autopsy studies on environmentally exposed humans as well as experimental studies on laboratory animals indicate that cesium is somewhat uniformly distributed in the body, with skeletal muscle gradually becoming the dominant repository. The half-time of the long-term component has been found to vary with age, gender, diet, race, muscle mass, pregnancy, and elevation above sea level (Lloyd et al, , 1973Zundel et al, 1969;Leggett, 1986;ICRP, 1989;Leggett et al, 2003). Cesium-137 is a beta emitter but is accompanied by the short-lived daughter 137m Ba that emits relatively energetic gamma radiation that allows external measurement of internal deposits.…”

“…Variability in cesium biokinetics in the population can be explained largely by differences in the mass of potassium in the body; the level of the hormone aldosterone in blood, which affects release of potassium and cesium from cells and the urinary excretion rate of cesium; and the level of potassium in diet (Leggett, 1986). The latter two factors are related, e.g., ingestion of a high-potassium diet increases aldosterone secretion.…”

Probabilistic accident consequence uncertainty analysis -- Uncertainty assessment for internal dosimetry. Volume 2: Appendices

“…The rate of loss of cesium from the body is increased, compared to adults, with the exception of neonates (ICRF' , 1990). Age-dependent variations in the retention of cesium in the body have been related to changes in body mass and body potassium content (Leggett, 1986).…”

“…To derive the values tabulated for Cs, the information summarized by Leggett (1986) and contained in two later papers, and , have been analyzed to provide assessments of the inter-individual variations in a group of 44 adult males and 12 adult females. The data presented in the response to Question 15 are for an average population of 50% males and 50% females and are derived assuming a two compartment exponential model:…”